If you ask children what color sunlight is, they will most likely tell you that light has no color or that the sun is yellow. You can use a glass of water or prism to illustrate that although light appears colorless, it contains every color in the rainbow. Place the water or prism in a sunny window, adjusting the placement until it catches the light and produces a rainbow. Let children take turns putting a white sheet of paper on the surface where the rainbow is reflected and trace the pattern with crayons, markers or colored pencils.
A bag of rainbow pasta gives children an opportunity to practice identifying, sorting or graphing colors. Give each student a diagram of a rainbow and a plastic bag of rainbow pasta. Students sort the pasta by color, matching each piece to the corresponding color arc on the diagram. Students can also graph the number of each color of pasta in the bag.
Rainbow art possibilities range from a simple painting or mosaic to a sun-catcher or mobile. You can introduce the children to crayon resist techniques by having them draw a rainbow in heavy crayon and painting over it with black or dark blue and white paint mixtures to simulate a cloudy sky. They can glue arcs of multi-colored cereal loops in a rainbow pattern on a piece of paper. Have students sprinkle crayon shavings in rainbow arcs in the correct color order on a sheet of wax paper; cover with another wax sheet and apply heat to fuse them together for a sun catcher. Cut a cloud and sun out of construction paper as well as an arc for each color of the rainbow. Lay the arcs out in color order and run a single string down the center, taping each arc to the string. Suspend the rainbow from the center of a chopstick and the sun and clouds to either side above it.
Celebrate the end of a rainbow study with an edible gelatin rainbow. You will need to start this activity several days in advance and complete one color per day to be ready just in time for the rainbow party. Have the children mix up one color at a time, starting with red and continuing in rainbow order. Pour it in a mold, letting each layer set overnight before adding the next layer. Pop the creation out of the mold at party time and admire the rainbow dessert before gobbling it down.